The two sides discussed humanitarian aid to the besieged city of Homs, according to Brahimi. The UN envoy said that if an agreement was reached on Sunday, a convoy could enter Homs as early as Monday.

"Nominally, tomorrow the governor [of Homs] is going to meet with his security advisor and we hope, ultimately at some point some convoy of aid goods, both food and non-food items and some medical supplies will be allowed to go into the old city," Brahimi told reporters.

"Tomorrow we will discuss the issue of prisoners, people that have been kidnapped," he said.

The meeting, during which the two sides also discussed preparations and a framework for further negotiations, lasted just 40 minutes. The peace talks in Switzerland are set to last for an initial period of a week.

Swift separation

The milestone morning meeting was short-lived; soon both sides returned to separate rooms and Brahimi began moving between them. He was expected to try to persuade the two parties to resume direct talks on humanitarian issues in the afternoon.

"We never expected this to be easy," Brahimi had told reporters on Friday. "I think the two parties understand what is at stake."

Pulled together by the United Nations, Russia and the United States, the two sides have met for the first time in the biggest diplomatic push yet to stem Syria's bloodshed after nearly three years of civil war.

Small progress

Despite the brevity of the morning session, the meeting still marked progress after a difficult first day for the talks saw President Bashar al-Assad's regime accuse the opposition of obstructing the negotiations and threatening to walk away.

Direct talks had been hampered by opposition demands that the regime be prepared to discuss Assad's stepping down, something the government has previously refused to do.

The opposition negotiator Abda said he expected that in "the first few days or maybe weeks" of talks the two sides would speak only through Brahimi.

Some 130,000 people are thought to have died so far in Syria in an uprising that initially began with peaceful protests against Assad in March 2011. The conflict has forced millions of people to flee their homes, as well as attracting al Qaeda-linked militants into the fray.